A smidge of science might help immeasurably at this time of year as we invite one of our favorites into the kitchen: the egg. You know, that sign of spring, the Easter thing.
For as simple as it appears, the egg is significantly complex. Knowing its science makes for better eating.
Its two main constituents — the white and the yolk — react to heat in different ways, and therein lies any difficulty in cooking.
The white is 88 percent water; the yolk, 50 percent. That moisture turns to steam when heated, the steam differently affecting the two kinds of proteins, in turn, in the white and in the yolk.
The white’s proteins are like a skein or ball of yarn. Heated, they untangle and bond to each other, becoming firmer and firmer and forcing out moisture, hardening finally into a rubbery mass.
The yolk’s proteins are spherical, and set inside each other, like thousands of Russian dolls. You’ll notice that, when overcooked, the yolk isn’t rubbery like overcooked white, but crumbles like chalk.
Basically, I’ve learned that successful poaching, hard cooking, scrambling and whipping (to give just four examples) depend on how I manage the two proteins in an egg. For example, my best soft-cooked eggs blast the whites with heat before slowly working their way into the refrigerator-cold yolk. (I want the white to end up soft at 180 degrees; the yolk to be runny at 155 degrees.)
So I place anywhere from four to eight eggs, just out of the refrigerator, into a bamboo steamer, already set over steaming, simmering water. (In Denver, that water is 200 degrees, not sea-level 212.) Either starting eggs in cold water in order to soft cook them, or adding a number of cold eggs into simply boiling water (which lowers the water’s temperature dramatically), doesn’t work. I want to give the super-hot water the chance to cook the whites to a higher temperature before it works its way into the yolk to do its job there.
Likewise, when scrambling eggs, I keep those protein structures in mind. (A more proper term would be “coagulating eggs,” because that’s what I’m doing to the proteins, but then what would a gazillion diner menus read?)
First, I salt the lightly whipped eggs at least 15 minutes before cooking them in a good amount of fat (read: butter). The salt gets in between the proteins and prevents them from bonding in the same way that they would without salt, so I get more control when the heat hits the pan.
The fat also slows down the untangling of the white’s proteins and the too-quick hardening of the yolk’s. The fat also gets in the way of the escape of steam, thus retaining more moisture in the finished scramble.
A couple more hints when dealing with eggs that acknowledge the egg’s science:
- Old eggs are easier to whip into peaks than fresh. As an egg ages (six to seven weeks out of its hen), its pH rises and the elevated acidity affects the electrical charge of its protein, in the same way that adding cream of tartar (powdered tartaric acid) does.
- The whites and yolks of fresh eggs are easier to separate because the membrane protecting the yolk (the vitelline) weakens with age. Also, separate eggs when they are cold rather than room temperature because the yolk is firmer in that state.
When you travel this summer, you’ll note that, in many countries, whole eggs are displayed on the counter, outside of any refrigeration. Unlike many other governments, ours mandates that fresh eggs be washed before sale and, in so doing, does away with a natural, protective cuticle given each egg on laying.
How to read the codes at the end of the egg carton: The three-digit number is the date the eggs were washed, graded and packed — not laid — construed as a “Julian” number (Jan. 1 is 001; Dec. 31 is 365). By law, an egg packer has 30 days after laying to pack an egg, although in practice the time is much shorter.
The sell-by date is not required but is often stamped on the carton. It cannot be more than 30 days after packing. Properly stored, eggs remain fresh and tasty two to three weeks after the sell-by date, although some things in them are compromised due mostly to evaporation from within the egg (an eggshell is pocked with around 10,000 microscopic pores, all of which easily “breathe” both air and moisture) and deterioration of some inner membranes or elements.
Today’s recipe is my mother’s. When she came from Belgium in the 1940s and eventually met my father, then married and set to their family-making, she did not know how to make an American-style pie (larded flaky crust, etc.). Belgians made “pies” called clafoutis, a sort of egg-and-flour “crust” in which sat fruit such as cherries or plums.
You’ll note the two-stage cooking of the egg-and-flour mix. It thereby cooks the two egg proteins at different stages and in different ways.
You may prepare the clafoutis in several vessels: an 8-inch spring-form pan, any oven-safe skillet, an oval gratin dish, even a Pyrex-style casserole. You may make this in individual ramekins or custard dishes. However, the cooking time and attention to detail will lengthen. (Also, if using the latter, use a bain marie.) For my part, I prefer a well-seasoned cast iron skillet. In a nice plus, it crisps up the bottom of this “pudding-like” pie.
- 2 tablespoons unsalted butter
- 3 large eggs, room temperature
- 2 tablespoons granulated sugar
- 1 cup whole milk
- 1/4 cup heavy cream
- 1/2 teaspoon almond extract
- 1/2 teaspoon vanilla extract
- 1/4 teaspoon salt
- 1/2 cup all-purpose (not self-rising) flour
- 3/4 teaspoon grated lemon zest
- 2-3 cups pitted cherries
- Powdered sugar fordusting at finish
Preheat the oven to 375. Place the butter in the cooking pan and set it aside for a moment.
In a large bowl, whisk together until super smooth the eggs, granulated sugar, milk, cream, flavoring extracts, salt, flour, and lemon zest. Set aside for a few moments to settle.
Place the cooking pan into the oven and, when the butter has melted, take out the pan and swirl it around to coat. Pour a half a cup of the egg-and-flour mix into the pan and place the pan back in the oven.
After 6-7 minutes, as the mix in the pan firms up slightly, take it out. Distribute the fruit evenly on top, and then add the remainder of the egg-and-flour mix.
Place back into the oven for 30-40 minutes, keeping an eye on it. The clafoutis will puff up and then sink, perhaps becoming slightly brown on top, but do not let it become crusted with anything resembling browned toast; that is too much. When done, a slim knife inserted into its center should draw out clean.
Remover the clafoutis and set it on a cooling rack or ventilated trivet.
In 3-4 minutes, run a knife around the edge of the pan; sprinkle the clafoutis with powdered sugar to taste; and begin to portion it out, in wedges or squares. It’s also great the next morning as a breakfast side.
Reach Bill St John at firstname.lastname@example.org